Sweet corn hybrid sv1321sd and parents thereof

ABSTRACT

The invention provides seed and plants of sweet corn hybrid SV1321SD and the parent lines thereof. The invention thus relates to the plants, seeds and tissue cultures of sweet corn hybrid SV1321SD and the parent lines thereof, and to methods for producing a sweet corn plant produced by crossing such plants with themselves or with another sweet corn plant, such as a plant of another genotype. The invention further relates to seeds and plants produced by such crossing. The invention further relates to parts of such plants, including the parts of such plants.

FIELD OF THE INVENTION

The present invention relates to the field of plant breeding and, morespecifically, to the development of sweet corn hybrid SV1321SD and theinbred sweet corn lines SYY-6R07001 and SHY-6RRVR242.

BACKGROUND OF THE INVENTION

The goal of vegetable breeding is to combine various desirable traits ina single variety/hybrid. Such desirable traits may include any traitdeemed beneficial by a grower and/or consumer, including greater yield,better stalks, better roots, resistance to insecticides, herbicides,pests, and disease, tolerance to heat and drought, reduced time to cropmaturity, better agronomic quality, higher nutritional value, sugarcontent, uniformity in germination times, stand establishment, growthrate and maturity, among others.

Breeding techniques take advantage of a plant's method of pollination.There are two general methods of pollination: a plant self-pollinates ifpollen from one flower is transferred to the same or another flower ofthe same plant or plant variety. A plant cross-pollinates if pollencomes to it from a flower of a different plant variety.

Plants that have been self-pollinated and selected for type over manygenerations become homozygous at almost all gene loci and produce auniform population of true breeding progeny, a homozygous plant. A crossbetween two such homozygous plants of different genotypes produces auniform population of hybrid plants that are heterozygous for many geneloci. Conversely, a cross of two plants each heterozygous at a number ofloci produces a population of hybrid plants that differ genetically andare not uniform. The resulting non-uniformity makes performanceunpredictable.

The development of uniform varieties requires the development ofhomozygous inbred plants, the crossing of these inbred plants, and theevaluation of the crosses. Pedigree breeding and recurrent selection areexamples of breeding methods that have been used to develop inbredplants from breeding populations. Those breeding methods combine thegenetic backgrounds from two or more plants or various other broad-basedsources into breeding pools from which new lines and hybrids derivedtherefrom are developed by selfing and selection of desired phenotypes.The new lines and hybrids are evaluated to determine which of those havecommercial potential.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a plant of the sweet cornhybrid designated SV1321SD, the sweet corn line SYY-6R07001 or sweetcorn line SHY-6RRVR242. Also provided are corn plants having all thephysiological and morphological characteristics of such a plant. Partsof these corn plants are also provided, for example, including pollen,an ovule, and a cell of the plant.

In another aspect of the invention, a plant of sweet corn hybridSV1321SD and/or sweet corn lines SYY-6R07001 and SHY-6RRVR242 comprisingan added heritable trait is provided. The heritable trait may comprise agenetic locus that is, for example, a dominant or recessive allele. Inone embodiment of the invention, a plant of sweet corn hybrid SV1321SDand/or sweet corn lines SYY-6R07001 and SHY-6RRVR242 is defined ascomprising a single locus conversion. In specific embodiments of theinvention, an added genetic locus confers one or more traits such as,for example, male sterility, herbicide resistance, insect resistance,resistance to bacterial, fungal, sugar content, nematode or viraldisease, and altered fatty acid, phytate or carbohydrate metabolism. Infurther embodiments, the trait may be conferred by a naturally occurringgene introduced into the genome of a line by backcrossing, a natural orinduced mutation, or a transgene introduced through genetictransformation techniques into the plant or a progenitor of any previousgeneration thereof. When introduced through transformation, a geneticlocus may comprise one or more genes integrated at a single chromosomallocation.

The invention also concerns the seed of sweet corn hybrid SV1321SDand/or sweet corn lines SYY-6R07001 and SHY-6RRVR242. The corn seed ofthe invention may be provided, in one embodiment of the invention, as anessentially homogeneous population of corn seed of sweet corn hybridSV1321SD and/or sweet corn lines SYY-6R07001 and SHY-6RRVR242.Essentially homogeneous populations of seed are generally free fromsubstantial numbers of other seed. Therefore, seed of hybrid SV1321SDand/or sweet corn lines SYY-6R07001 and SHY-6RRVR242 may, in particularembodiments of the invention, be provided forming at least about 97% ofthe total seed, including at least about 98%, 99% or more of the seed.The seed population may be separately grown to provide an essentiallyhomogeneous population of sweet corn plants designated SV1321SD and/orsweet corn lines SYY-6R07001 and SHY-6RRVR242.

In yet another aspect of the invention, a tissue culture of regenerablecells of a sweet corn plant of hybrid SV1321SD and/or sweet corn linesSYY-6R07001 and SHY-6RRVR242 is provided. The tissue culture willpreferably be capable of regenerating corn plants capable of expressingall of the physiological and morphological characteristics of thestarting plant, and of regenerating plants having substantially the samegenotype as the starting plant. Examples of some of the physiologicaland morphological characteristics of the hybrid SV1321SD and/or sweetcorn lines SYY-6R07001 and SHY-6RRVR242 include those traits set forthin the tables herein. The regenerable cells in such tissue cultures maybe derived, for example, from embryos, meristematic cells, immaturetassels, microspores, pollen, leaves, anthers, roots, root tips, silk,flowers, kernels, ears, cobs, husks, or stalks, or from callus orprotoplasts derived from those tissues. Still further, the presentinvention provides corn plants regenerated from a tissue culture of theinvention, the plants having all the physiological and morphologicalcharacteristics of hybrid SV1321SD and/or sweet corn lines SYY-6R07001and SHY-6RRVR242.

In still yet another aspect of the invention, processes are provided forproducing corn seeds, plants and parts thereof, which processesgenerally comprise crossing a first parent corn plant with a secondparent corn plant, wherein at least one of the first or second parentcorn plants is a plant of sweet corn line SYY-6R07001 or sweet corn lineSHY-6RRVR242. These processes may be further exemplified as processesfor preparing hybrid corn seed or plants, wherein a first corn plant iscrossed with a second corn plant of a different, distinct genotype toprovide a hybrid that has, as one of its parents, a plant of sweet cornline SYY-6R07001 or sweet corn line SHY-6RRVR242. In these processes,crossing will result in the production of seed. The seed productionoccurs regardless of whether the seed is collected or not.

In one embodiment of the invention, the first step in “crossing”comprises planting seeds of a first and second parent corn plant, oftenin proximity so that pollination will occur for example, naturally ormanually. Where the plant is self-pollinated, pollination may occurwithout the need for direct human intervention other than plantcultivation. For hybrid crosses, it may be beneficial to detassel orotherwise emasculate the parent used as a female.

A second step may comprise cultivating or growing the seeds of first andsecond parent corn plants into mature plants. A third step may comprisepreventing self-pollination of the plants, such as by detasseling orother means.

A fourth step for a hybrid cross may comprise cross-pollination betweenthe first and second parent corn plants. Yet another step comprisesharvesting the seeds from at least one of the parent corn plants. Theharvested seed can be grown to produce a corn plant or hybrid cornplant.

The present invention also provides the corn seeds and plants producedby a process that comprises crossing a first parent corn plant with asecond parent corn plant, wherein at least one of the first or secondparent corn plants is a plant of sweet corn hybrid SV1321SD and/or sweetcorn lines SYY-6R07001 and SHY-6RRVR242. In one embodiment of theinvention, corn seed and plants produced by the process are firstgeneration (F₁) hybrid corn seed and plants produced by crossing a plantin accordance with the invention with another, distinct plant. Thepresent invention further contemplates plant parts of such an F₁ hybridcorn plant, and methods of use thereof. Therefore, certain exemplaryembodiments of the invention provide an F₁ hybrid corn plant and seedthereof.

In still yet another aspect, the present invention provides a method ofproducing a plant derived from hybrid SV1321SD and/or sweet corn linesSYY-6R07001 and SHY-6RRVR242, the method comprising the steps of: (a)preparing a progeny plant derived from hybrid SV1321SD and/or sweet cornlines SYY-6R07001 and SHY-6RRVR242, wherein said preparing comprisescrossing a plant of the hybrid SV1321SD and/or sweet corn linesSYY-6R07001 and SHY-6RRVR242 with a second plant; and (b) crossing theprogeny plant with itself or a second plant to produce a seed of aprogeny plant of a subsequent generation. In further embodiments, themethod may additionally comprise: (c) growing a progeny plant of asubsequent generation from said seed of a progeny plant of a subsequentgeneration and crossing the progeny plant of a subsequent generationwith itself or a second plant; and repeating the steps for an additional3-10 generations to produce a plant derived from hybrid SV1321SD and/orsweet corn lines SYY-6R07001 and SHY-6RRVR242. The plant derived fromhybrid SV1321SD and/or sweet corn lines SYY-6R07001 and SHY-6RRVR242 maybe an inbred line, and the aforementioned repeated crossing steps may bedefined as comprising sufficient inbreeding to produce the inbred line.In the method, it may be desirable to select particular plants resultingfrom step (c) for continued crossing according to steps (b) and (c). Byselecting plants having one or more desirable traits, a plant derivedfrom hybrid SV1321SD and/or sweet corn lines SYY-6R07001 andSHY-6RRVR242 is obtained which possesses some of the desirable traits ofthe line/hybrid as well as potentially other selected traits.

In certain embodiments, the present invention provides a method ofproducing food or feed comprising: (a) obtaining a plant of sweet cornhybrid SV1321SD and/or sweet corn lines SYY-6R07001 and SHY-6RRVR242,wherein the plant has been cultivated to maturity, and (b) collecting atleast one corn from the plant.

In still yet another aspect of the invention, the genetic complement ofsweet corn hybrid SV1321SD and/or sweet corn lines SYY-6R07001 andSHY-6RRVR242 is provided. The phrase “genetic complement” is used torefer to the aggregate of nucleotide sequences, the expression of whichsequences defines the phenotype of, in the present case, a sweet cornplant, or a cell or tissue of that plant. A genetic complement thusrepresents the genetic makeup of a cell, tissue or plant, and a hybridgenetic complement represents the genetic make up of a hybrid cell,tissue or plant. The invention thus provides corn plant cells that havea genetic complement in accordance with the corn plant cells disclosedherein, and seeds and plants containing such cells.

Plant genetic complements may be assessed by genetic marker profiles,and by the expression of phenotypic traits that are characteristic ofthe expression of the genetic complement, e.g., isozyme typing profiles.It is understood that hybrid SV1321SD and/or sweet corn linesSYY-6R07001 and SHY-6RRVR242 could be identified by any of the many wellknown techniques such as, for example, Simple Sequence LengthPolymorphisms (SSLPs) (Williams et al., Nucleic Acids Res., 18:6531-6535, 1990), Randomly Amplified Polymorphic DNAs (RAPDs), DNAAmplification Fingerprinting (DAF), Sequence Characterized AmplifiedRegions (SCARs), Arbitrary Primed Polymerase Chain Reaction (AP-PCR),Amplified Fragment Length Polymorphisms (AFLPs) (EP 534 858,specifically incorporated herein by reference in its entirety), andSingle Nucleotide Polymorphisms (SNPs) (Wang et al., Science,280:1077-1082, 1998).

In still yet another aspect, the present invention provides hybridgenetic complements, as represented by corn plant cells, tissues,plants, and seeds, formed by the combination of a haploid geneticcomplement of a corn plant of the invention with a haploid geneticcomplement of a second corn plant, preferably, another, distinct cornplant. In another aspect, the present invention provides a corn plantregenerated from a tissue culture that comprises a hybrid geneticcomplement of this invention.

In still yet another aspect, the invention provides a method ofdetermining the genotype of a plant of sweet corn hybrid SV1321SD and/orsweet corn lines SYY-6R07001 and SHY-6RRVR242 comprising detecting inthe genome of the plant at least a first polymorphism. The method may,in certain embodiments, comprise detecting a plurality of polymorphismsin the genome of the plant. The method may further comprise storing theresults of the step of detecting the plurality of polymorphisms on acomputer readable medium. The invention further provides a computerreadable medium produced by such a method.

Any embodiment discussed herein with respect to one aspect of theinvention applies to other aspects of the invention as well, unlessspecifically noted.

The term “about” is used to indicate that a value includes the standarddeviation of the mean for the device or method being employed todetermine the value. The use of the term “or” in the claims is used tomean “and/or” unless explicitly indicated to refer to alternatives onlyor the alternatives are mutually exclusive. When used in conjunctionwith the word “comprising” or other open language in the claims, thewords “a” and “an” denote “one or more,” unless specifically notedotherwise. The terms “comprise,” “have” and “include” are open-endedlinking verbs. Any forms or tenses of one or more of these verbs, suchas “comprises,” “comprising,” “has,” “having,” “includes” and“including,” are also open-ended. For example, any method that“comprises,” “has” or “includes” one or more steps is not limited topossessing only those one or more steps and also covers other unlistedsteps. Similarly, any plant that “comprises,” “has” or “includes” one ormore traits is not limited to possessing only those one or more traitsand covers other unlisted traits.

Other objects, features and advantages of the present invention willbecome apparent from the following detailed description. It should beunderstood, however, that the detailed description and any specificexamples provided, while indicating specific embodiments of theinvention, are given by way of illustration only, since various changesand modifications within the spirit and scope of the invention willbecome apparent to those skilled in the art from this detaileddescription.

DETAILED DESCRIPTION OF THE INVENTION

The invention provides methods and compositions relating to plants,seeds and derivatives of sweet corn hybrid SV1321SD, sweet corn lineSYY-6R07001 and sweet corn line SHY-6RRVR242. The hybrid SV1321SD wasproduced by the cross of parent lines SYY-6R07001 and SHY-6RRVR242. Theparent lines show uniformity and stability within the limits ofenvironmental influence. By crossing the parent lines, uniform seedhybrid SV1321SD can be obtained.

Hybrid SV1321SD is a yellow supersweet corn hybrid. SV1321SD has the RpGgene which provides resistance to some races of Puccinia sorghi (commonrust). One parent is homozygous recessive for both the sh2 and su1 genesand the other parent is homozygous recessive for the sh2 gene buthomozygous dominant for the Su1 gene.

The development of sweet corn hybrid SV1321SD and its parent lines issummarized below.

A. Origin and Breeding History of Sweet Corn Hybrid SV1321SD

The hybrid SV1321SD, also known as QHY6SH1321, was produced by the crossof parent lines SYY-6R07001 and SHY-6RRVR242.

B. Physiological and Morphological Characteristics of Sweet Corn HybridSV1321SD, Sweet Corn Line SYY-6R07001 and Sweet Corn Line SHY-6RRVR242

In accordance with one aspect of the present invention, there isprovided a plant having the physiological and morphologicalcharacteristics of sweet corn hybrid SV1321SD and the parent linesthereof. A description of the physiological and morphologicalcharacteristics of such plants is presented in Table 1.

TABLE 1 Physiological and Morphological Characteristics of HybridSV1321SD Standard Inbred: Characteristic SV1321SD PASSION Type sweetsweet Maturity in the Region of Best Adaptability from emergence to 50%of days: 49 days: 49 heat units: plants in silk heat units: 956.4 956.4from emergence to 50% of days: 46 days: 47 plants in pollen heat units:909.3 heat units: 925.4 from 10% to 90% pollen shed days: 7  days: 6 heat units: 127.5 heat units: 107.7 from 50% silk to optimum days: 20days: 20 edible quality heat units: 402.3 heat units: 402.3 from 50%silk to harvest at days: 55 days: 55 25% moisture heat units: 1110.3heat units: 1110.3 foliage: intensity of green dark dark color firstleaf: anthocyanin absent or very weak absent or very weak coloration ofsheath first leaf: shape of apex pointed pointed leaf: undulation ofmargin of intermediate intermediate blade leaf: angle between blade andmedium (±50°) medium (±50°) stem (on leaf just above upper ear) leaf:curvature of blade moderately recurved moderately recurved leaf:anthocyanin coloration absent or very weak absent or very weak of sheath(in middle of plant) leaf: width of blade medium medium leaf: width ofear node leaf in  7.5 cm  8.6 cm centimeters standard deviation:standard deviation: 0.73 0.46 sample size: 15 sample size: 15 leaf:length of ear node leaf in 64.6 cm 79.9 cm centimeters standarddeviation: standard deviation: 4.64 2.34 sample size: 15 sample size: 15leaf: number of leaves above 6.4 6.2 top ear standard deviation:standard deviation: 0.63 0.7 sample size: 15 sample size: 15 leaf:degrees leaf angle 50° 50° leaf: color 5GY4/4 5GY4/4 leaf: sheathpubescence 7 6 leaf: marginal waves 4 3 leaf: longitudinal creases 6 6stem: degree of zig-zag slight absent or very slight stem: anthocyanincoloration absent or very weak absent or very weak of brace roots stem:anthocyanin coloration absent or very weak absent or very weak ofinternodes Plant only inbred lines and varieties medium medium with eartype of grain: sweet or pop: plant length (tassel included) ratio heightof insertion of medium small peduncle of upper ear to plant lengthpeduncle: length medium long plant height (to tassel tip) 162.6 cm 187.4 cm  standard deviation: standard deviation 10.51 6.81 sample size:15 sample size: 15 ear height (to base of top ear 35.7 cm 58.7 cm node)standard deviation: standard deviation 3.83 8.66 sample size: 15 samplesize: 15 length of top ear internode 13.5 cm 14.1 cm standard deviation:standard deviation: 1.16 1.25 sample size: 15 sample size: 15 averagenumber of tillers 2.6 avg 3.4 avg standard deviation: standard deviation0.83 1.18 sample size: 15 sample size: 15 average number of ears per 1.6avg 2.4 avg stalk standard deviation: standard deviation: 0.49 0.52sample size: 15 sample size: 15 anthocyanin of brace roots absent absentTassel time of anthesis medium medium anthocyanin coloration at baseabsent or very weak absent or very weak of glume anthocyanin colorationof absent or very weak absent or very weak glumes excluding baseanthocyanin coloration of absent or very weak absent or very weakanthers (in middle third of main axis) angle between main axis and large±75° medium ±50° lateral branches (in lower third of tassel curvature oflateral branches strongly recurved moderately recurved (in lower thirdof tassel) number of primary lateral medium many branches density ofspikelets medium moderately dense length of main axis above very longvery long lowest later branch (A-B) length of main axis above mediumlong highest lateral branch (C-D) length of lateral branch long mediumnumber of primary lateral 29.2 31.9 branches standard deviation:standard deviation: 3.03 3.61 sample size: 15 sample size: 15 branchangle from central 69.1°   53.6°   spike standard deviation: standarddeviation: 16.4 6.67 sample size: 15 sample size: 15 tassel length (fromtop leaf 39.9 cm 41.1 cm collar to tassel tip) in standard deviation:standard deviation: centimeters 3.06 2.59 sample size: 15 sample size:15 pollen shed 7 45 anther color   5GY6/6 5GY7/6 glume color 2.5GY7/65GY6/4 bar glumes (glume bands) absent absent Ear (unhusked data): silkcolor 2.5GY8/6 2.5GY7/6 (unhusked data): fresh husk 2.5GY7/8 2.5GY6/8color (unhusked data): dry husk 2.5Y8/4 2.5Y8/4 color (unhusked data):position of upright upright ear at dry husk stage (unhusked data): husk8 5 tightness (unhusked data): husk medium (<8 cm) medium (<8 cm)extension (at harvest) (husked ear data): ear length   19 cm 19.6 cm incentimeters standard deviation: standard deviation: 1.46 0.8 samplesize: 15 sample size: 15 (husked ear data): ear 50.6 mm 45.4 cm diameterat mid-point in standard deviation: standard deviation: millimeters 2.962.02 sample size: 15 sample size: 15 (husked ear data): ear weight 109.2gm 110.3 gm in grams standard deviation: standard deviation: 25.86 18.28sample size: 15 sample size: 15 (husked ear data): number of 19.9 18.7kernel rows standard deviation: standard deviation: 2.02 1.33 samplesize: 15 sample size: 15 (husked ear data): kernel rows distinctdistinct (husked ear data): row slightly curved straight alignment(husked ear data): shank 14 cm 21.3 cm length in centimeters standarddeviation: standard deviation: 3.05 2.54 sample size: 15 sample size: 15(husked ear data): ear taper average average length medium mediumdiameter ( in middle) large medium shape cylindrical conico-clindricalnumber of rows of grain many many number of colors of grains one one(only varieties with ear type of grain: sweet or waxy) grain: intensityof yellow dark dark color (only varieties with ear type of grain: sweet)grain: length (only varieties medium long with ear type of grain: sweet)grain: width (only varieties medium medium with ear type of grain) typeof grain sweet sweet shrinkage of top of grain (only strong strongvarieties with ear type of grain: sweet) color of top of grain orangeyellow orange anthocyanin coloration of absent or very weak absent orvery weak glumes of cob time of silk emergence (50% medium medium ofplants) anthocyanin coloration of absent or very weak absent or veryweak silks Cob diameter at mid-point   29 mm  28.4 mm standarddeviation: standard deviation: 0.99 1.33 sample size: 15 sample size: 15color 5Y 8/4 5Y 8/4 Kernel (dried) length 9.8 mm 11.8 mm standarddeviation: standard deviation: 0.8 0.65 sample size: 15 sample size: 15width 5.3 mm 6.1 mm standard deviation: standard deviation: 0.85 0.55sample size: 15 sample size: 15 thickness 3.6 mm 3.8 mm standarddeviation: standard deviation 0.91 0.87 sample size: 15 sample size: 15% round kernels (shape grade) 0.50%   0.30%   sample size: n/a samplesize: n/a aleurone color pattern homozygous homozygous aleurone color7.5YR7/10 2.5Y7/10 hard endosperm color 7.5YR7/10 2.5Y7/10 endospermtype sweet (su1) sweet (su1) weight per 100 kernels 12 gm 8 gm (unsizedsample) sample size: n/a sample size: n/a Agronomic Traits stay green(at 65 days after 8 6 anthesis) (from 1 = worst to 9 = excellent)dropped ears 0% 0% % pre-anthesis brittle 0% 0% snapping % pre-anthesisroot lodging 0% 0% post-anthesis root lodging 0% 0% *These are typicalvalues. Values may vary due to environment. Other values that aresubstantially equivalent are also within the scope of the invention.

C. Breeding Corn Plants

One aspect of the current invention concerns methods for producing seedof sweet corn hybrid SV1321SD involving crossing sweet corn linesSYY-6R07001 and SHY-6RRVR242. Alternatively, in other embodiments of theinvention, hybrid SV1321SD, line SYY-6R07001, or line SHY-6RRVR242 maybe crossed with itself or with any second plant. Such methods can beused for propagation of hybrid SV1321SD and/or the sweet corn linesSYY-6R07001 and SHY-6RRVR242, or can be used to produce plants that arederived from hybrid SV1321SD and/or the sweet corn lines SYY-6R07001 andSHY-6RRVR242. Plants derived from hybrid SV1321SD and/or the sweet cornlines SYY-6R07001 and SHY-6RRVR242 may be used, in certain embodiments,for the development of new corn varieties.

The development of new varieties using one or more starting varieties iswell known in the art. In accordance with the invention, novel varietiesmay be created by crossing hybrid SV1321SD followed by multiplegenerations of breeding according to such well known methods. Newvarieties may be created by crossing with any second plant. In selectingsuch a second plant to cross for the purpose of developing novel lines,it may be desired to choose those plants which either themselves exhibitone or more selected desirable characteristics or which exhibit thedesired characteristic(s) when in hybrid combination. Once initialcrosses have been made, inbreeding and selection take place to producenew varieties. For development of a uniform line, often five or moregenerations of selfing and selection are involved.

Uniform lines of new varieties may also be developed by way ofdouble-haploids. This technique allows the creation of true breedinglines without the need for multiple generations of selfing andselection. In this manner true breeding lines can be produced in aslittle as one generation. Haploid embryos may be produced frommicrospores, pollen, anther cultures, or ovary cultures. The haploidembryos may then be doubled autonomously, or by chemical treatments(e.g. colchicine treatment). Alternatively, haploid embryos may be growninto haploid plants and treated to induce chromosome doubling. In eithercase, fertile homozygous plants are obtained. In accordance with theinvention, any of such techniques may be used in connection with a plantof the invention and progeny thereof to achieve a homozygous line.

Backcrossing can also be used to improve an inbred plant. Backcrossingtransfers a specific desirable trait from one inbred or non-inbredsource to an inbred that lacks that trait. This can be accomplished, forexample, by first crossing a superior inbred (A) (recurrent parent) to adonor inbred (non-recurrent parent), which carries the appropriate locusor loci for the trait in question. The progeny of this cross are thenmated back to the superior recurrent parent (A) followed by selection inthe resultant progeny for the desired trait to be transferred from thenon-recurrent parent. After five or more backcross generations withselection for the desired trait, the progeny have the characteristicbeing transferred, but are like the superior parent for most or almostall other loci. The last backcross generation would be selfed to givepure breeding progeny for the trait being transferred.

The plants of the present invention are particularly well suited for thedevelopment of new lines based on the elite nature of the geneticbackground of the plants. In selecting a second plant to cross withSV1321SD and/or sweet corn lines SYY-6R07001 and SHY-6RRVR242 for thepurpose of developing novel corn lines, it will typically be preferredto choose those plants which either themselves exhibit one or moreselected desirable characteristics or which exhibit the desiredcharacteristic(s) when in hybrid combination. Examples of desirabletraits may include, in specific embodiments, male sterility, herbicideresistance, resistance for bacterial, fungal, or viral disease, insectresistance, male fertility, sugar content, and enhanced nutritionalquality.

D. Further Embodiments of the Invention

In certain aspects of the invention, plants described herein areprovided modified to include at least a first desired heritable trait.Such plants may, in one embodiment, be developed by a plant breedingtechnique called backcrossing, wherein essentially all of themorphological and physiological characteristics of a variety arerecovered in addition to a genetic locus transferred into the plant viathe backcrossing technique. The term single locus converted plant asused herein refers to those corn plants which are developed by a plantbreeding technique called backcrossing, wherein essentially all of themorphological and physiological characteristics of a variety arerecovered in addition to the single locus transferred into the varietyvia the backcrossing technique. By essentially all of the morphologicaland physiological characteristics, it is meant that the characteristicsof a plant are recovered that are otherwise present when compared in thesame environment, other than an occasional variant trait that mightarise during backcrossing or direct introduction of a transgene.

Backcrossing methods can be used with the present invention to improveor introduce a characteristic into the present variety. The parentalcorn plant which contributes the locus for the desired characteristic istermed the nonrecurrent or donor parent. This terminology refers to thefact that the nonrecurrent parent is used one time in the backcrossprotocol and therefore does not recur. The parental corn plant to whichthe locus or loci from the nonrecurrent parent are transferred is knownas the recurrent parent as it is used for several rounds in thebackcrossing protocol.

In a typical backcross protocol, the original variety of interest(recurrent parent) is crossed to a second variety (nonrecurrent parent)that carries the single locus of interest to be transferred. Theresulting progeny from this cross are then crossed again to therecurrent parent and the process is repeated until a corn plant isobtained wherein essentially all of the morphological and physiologicalcharacteristics of the recurrent parent are recovered in the convertedplant, in addition to the single transferred locus from the nonrecurrentparent.

The selection of a suitable recurrent parent is an important step for asuccessful backcrossing procedure. The goal of a backcross protocol isto alter or substitute a single trait or characteristic in the originalvariety. To accomplish this, a single locus of the recurrent variety ismodified or substituted with the desired locus from the nonrecurrentparent, while retaining essentially all of the rest of the desiredgenetic, and therefore the desired physiological and morphologicalconstitution of the original variety. The choice of the particularnonrecurrent parent will depend on the purpose of the backcross; one ofthe major purposes is to add some commercially desirable trait to theplant. The exact backcrossing protocol will depend on the characteristicor trait being altered and the genetic distance between the recurrentand nonrecurrent parents. Although backcrossing methods are simplifiedwhen the characteristic being transferred is a dominant allele, arecessive allele, or an additive allele (between recessive anddominant), may also be transferred. In this instance it may be necessaryto introduce a test of the progeny to determine if the desiredcharacteristic has been successfully transferred.

In one embodiment, progeny corn plants of a backcross in which a plantdescribed herein is the recurrent parent comprise (i) the desired traitfrom the non-recurrent parent and (ii) all of the physiological andmorphological characteristics of corn the recurrent parent as determinedat the 5% significance level when grown in the same environmentalconditions.

New varieties can also be developed from more than two parents. Thetechnique, known as modified backcrossing, uses different recurrentparents during the backcrossing. Modified backcrossing may be used toreplace the original recurrent parent with a variety having certain moredesirable characteristics or multiple parents may be used to obtaindifferent desirable characteristics from each.

With the development of molecular markers associated with particulartraits, it is possible to add additional traits into an established germline, such as represented here, with the end result being substantiallythe same base germplasm with the addition of a new trait or traits.Molecular breeding, as described in Moose and Mumm, 2008 (PlantPhysiology, 147: 969-977), for example, and elsewhere, provides amechanism for integrating single or multiple traits or QTL into an eliteline. This molecular breeding-facilitated movement of a trait or traitsinto an elite line may encompass incorporation of a particular genomicfragment associated with a particular trait of interest into the eliteline by the mechanism of identification of the integrated genomicfragment with the use of flanking or associated marker assays. In theembodiment represented here, one, two, three or four genomic loci, forexample, may be integrated into an elite line via this methodology. Whenthis elite line containing the additional loci is further crossed withanother parental elite line to produce hybrid offspring, it is possibleto then incorporate at least eight separate additional loci into thehybrid. These additional loci may confer, for example, such traits as adisease resistance or a fruit quality trait. In one embodiment, eachlocus may confer a separate trait. In another embodiment, loci may needto be homozygous and exist in each parent line to confer a trait in thehybrid. In yet another embodiment, multiple loci may be combined toconfer a single robust phenotype of a desired trait.

Many single locus traits have been identified that are not regularlyselected for in the development of a new inbred but that can be improvedby backcrossing techniques. Single locus traits may or may not betransgenic; examples of these traits include, but are not limited to,male sterility, waxy starch, herbicide resistance, resistance forbacterial, fungal, or viral disease, insect resistance, sugar content,male fertility and enhanced nutritional quality. These genes aregenerally inherited through the nucleus, but may be inherited throughthe cytoplasm. Some known exceptions to this are genes for malesterility, some of which are inherited cytoplasmically, but still act asa single locus trait.

Direct selection may be applied where the single locus acts as adominant trait. For this selection process, the progeny of the initialcross are assayed for viral resistance and/or the presence of thecorresponding gene prior to the backcrossing. Selection eliminates anyplants that do not have the desired gene and resistance trait, and onlythose plants that have the trait are used in the subsequent backcross.This process is then repeated for all additional backcross generations.

Selection of corn plants for breeding is not necessarily dependent onthe phenotype of a plant and instead can be based on geneticinvestigations. For example, one can utilize a suitable genetic markerwhich is closely genetically linked to a trait of interest. One of thesemarkers can be used to identify the presence or absence of a trait inthe offspring of a particular cross, and can be used in selection ofprogeny for continued breeding. This technique is commonly referred toas marker assisted selection. Any other type of genetic marker or otherassay which is able to identify the relative presence or absence of atrait of interest in a plant can also be useful for breeding purposes.Procedures for marker assisted selection are well known in the art. Suchmethods will be of particular utility in the case of recessive traitsand variable phenotypes, or where conventional assays may be moreexpensive, time consuming or otherwise disadvantageous. Types of geneticmarkers which could be used in accordance with the invention include,but are not necessarily limited to, Simple Sequence Length Polymorphisms(SSLPs) (Williams et al., Nucleic Acids Res., 1 8:6531-6535, 1990),Randomly Amplified Polymorphic DNAs (RAPDs), DNA AmplificationFingerprinting (DAF), Sequence Characterized Amplified Regions (SCARs),Arbitrary Primed Polymerase Chain Reaction (AP-PCR), Amplified FragmentLength Polymorphisms (AFLPs) (EP 534 858, specifically incorporatedherein by reference in its entirety), and Single NucleotidePolymorphisms (SNPs) (Wang et al., Science, 280:1077-1082, 1998).

E. Plants Derived by Genetic Engineering

Many useful traits that can be introduced by backcrossing, as well asdirectly into a plant, are those which are introduced by genetictransformation techniques. Genetic transformation may therefore be usedto insert a selected transgene into a plant of the invention or may,alternatively, be used for the preparation of transgenes which can beintroduced by backcrossing. Methods for the transformation of plantsthat are well known to those of skill in the art and applicable to manycrop species include, but are not limited to, electroporation,microprojectile bombardment, Agrobacterium-mediated transformation anddirect DNA uptake by protoplasts.

To effect transformation by electroporation, one may employ eitherfriable tissues, such as a suspension culture of cells or embryogeniccallus or alternatively one may transform immature embryos or otherorganized tissue directly. In this technique, one would partiallydegrade the cell walls of the chosen cells by exposing them topectin-degrading enzymes (pectolyases) or mechanically wound tissues ina controlled manner.

An efficient method for delivering transforming DNA segments to plantcells is microprojectile bombardment. In this method, particles arecoated with nucleic acids and delivered into cells by a propellingforce. Exemplary particles include those comprised of tungsten,platinum, and preferably, gold. For the bombardment, cells in suspensionare concentrated on filters or solid culture medium. Alternatively,immature embryos or other target cells may be arranged on solid culturemedium. The cells to be bombarded are positioned at an appropriatedistance below the macroprojectile stopping plate.

An illustrative embodiment of a method for delivering DNA into plantcells by acceleration is the Biolistics Particle Delivery System, whichcan be used to propel particles coated with DNA or cells through ascreen, such as a stainless steel or Nytex screen, onto a surfacecovered with target cells. The screen disperses the particles so thatthey are not delivered to the recipient cells in large aggregates.Microprojectile bombardment techniques are widely applicable, and may beused to transform virtually any plant species.

Agrobacterium-mediated transfer is another widely applicable system forintroducing gene loci into plant cells. An advantage of the technique isthat DNA can be introduced into whole plant tissues, thereby bypassingthe need for regeneration of an intact plant from a protoplast. ModernAgrobacterium transformation vectors are capable of replication in E.coli as well as Agrobacterium, allowing for convenient manipulations(Klee et al., Bio-Technology, 3(7):637-642, 1985). Moreover, recenttechnological advances in vectors for Agrobacterium-mediated genetransfer have improved the arrangement of genes and restriction sites inthe vectors to facilitate the construction of vectors capable ofexpressing various polypeptide coding genes. The vectors described haveconvenient multi-linker regions flanked by a promoter and apolyadenylation site for direct expression of inserted polypeptidecoding genes. Additionally, Agrobacterium containing both armed anddisarmed Ti genes can be used for transformation.

In those plant strains where Agrobacterium-mediated transformation isefficient, it is the method of choice because of the facile and definednature of the gene locus transfer. The use of Agrobacterium-mediatedplant integrating vectors to introduce DNA into plant cells is wellknown in the art (Fraley et al., Bio/Technology, 3:629-635, 1985; U.S.Pat. No. 5,563,055).

Transformation of plant protoplasts also can be achieved using methodsbased on calcium phosphate precipitation, polyethylene glycol treatment,electroporation, and combinations of these treatments (see, e.g.,Potrykus et al., Mol. Gen. Genet., 199:183-188, 1985; Omirulleh et al.,Plant Mol. Biol., 21(3):415-428, 1993; Fromm et al., Nature,312:791-793, 1986; Uchimiya et al., Mol. Gen. Genet., 204:204, 1986;Marcotte et al., Nature, 335:454, 1988). Transformation of plants andexpression of foreign genetic elements is exemplified in Choi et al.(Plant Cell Rep., 13: 344-348, 1994), and Ellul et al. (Theor. Appl.Genet., 107:462-469, 2003).

A number of promoters have utility for plant gene expression for anygene of interest including but not limited to selectable markers,scoreable markers, genes for pest tolerance, disease resistance,nutritional enhancements and any other gene of agronomic interest.Examples of constitutive promoters useful for plant gene expressioninclude, but are not limited to, the cauliflower mosaic virus (CaMV)P-35S promoter, which confers constitutive, high-level expression inmost plant tissues (see, e.g., Odel et al., Nature, 313:810, 1985),including in monocots (see, e.g., Dekeyser et al., Plant Cell, 2:591,1990; Terada and Shimamoto, Mol. Gen. Genet., 220:389, 1990); a tandemlyduplicated version of the CaMV 35S promoter, the enhanced 35S promoter(P-e35S);1 the nopaline synthase promoter (An et al., Plant Physiol.,88:547, 1988); the octopine synthase promoter (Fromm et al., Plant Cell,1:977, 1989); and the figwort mosaic virus (P-FMV) promoter as describedin U.S. Pat. No. 5,378,619 and an enhanced version of the FMV promoter(P-eFMV) where the promoter sequence of P-FMV is duplicated in tandem;the cauliflower mosaic virus 19S promoter; a sugarcane bacilliform viruspromoter; a commelina yellow mottle virus promoter; and other plant DNAvirus promoters known to express in plant cells.

A variety of plant gene promoters that are regulated in response toenvironmental, hormonal, chemical, and/or developmental signals can alsobe used for expression of an operably linked gene in plant cells,including promoters regulated by (1) heat (Callis et al., PlantPhysiol., 88:965, 1988), (2) light (e.g., pea rbcS-3A promoter,Kuhlemeier et al., Plant Cell, 1:471, 1989; maize rbcS promoter,Schaffner and Sheen, Plant Cell, 3:997, 1991; or chlorophyll a/b-bindingprotein promoter, Simpson et al., EMBO J., 4:2723, 1985), (3) hormones,such as abscisic acid (Marcotte et al., Plant Cell, 1:969, 1989), (4)wounding (e.g., wunl, Siebertz et al., Plant Cell, 1:961, 1989); or (5)chemicals such as methyl jasmonate, salicylic acid, or Safener. It mayalso be advantageous to employ organ-specific promoters (e.g., Roshal etal., EMBO J., 6:1155, 1987; Schernthaner et al., EMBO J., 7:1249, 1988;Bustos et al., Plant Cell, 1:839, 1989).

Exemplary nucleic acids which may be introduced to plants of thisinvention include, for example, DNA sequences or genes from anotherspecies, or even genes or sequences which originate with or are presentin the same species, but are incorporated into recipient cells bygenetic engineering methods rather than classical reproduction orbreeding techniques. However, the term “exogenous” is also intended torefer to genes that are not normally present in the cell beingtransformed, or perhaps simply not present in the form, structure, etc.,as found in the transforming DNA segment or gene, or genes which arenormally present and that one desires to express in a manner thatdiffers from the natural expression pattern, e.g., to over-express.Thus, the term “exogenous” gene or DNA is intended to refer to any geneor DNA segment that is introduced into a recipient cell, regardless ofwhether a similar gene may already be present in such a cell. The typeof DNA included in the exogenous DNA can include DNA which is alreadypresent in the plant cell, DNA from another plant, DNA from a differentorganism, or a DNA generated externally, such as a DNA sequencecontaining an antisense message of a gene, or a DNA sequence encoding asynthetic or modified version of a gene.

Many hundreds if not thousands of different genes are known and couldpotentially be introduced into a corn plant according to the invention.Non-limiting examples of particular genes and corresponding phenotypesone may choose to introduce into a corn plant include one or more genesfor insect tolerance, such as a Bacillus thuringiensis (B.t.) gene, pesttolerance such as genes for fungal disease control, herbicide tolerancesuch as genes conferring glyphosate tolerance, and genes for qualityimprovements such as yield, nutritional enhancements, environmental orstress tolerances, or any desirable changes in plant physiology, growth,development, morphology or plant product(s). For example, structuralgenes would include any gene that confers insect tolerance including butnot limited to a Bacillus insect control protein gene as described in WO99/31248, herein incorporated by reference in its entirety, U.S. Pat.No. 5,689,052, herein incorporated by reference in its entirety, U.S.Pat. Nos. 5,500,365 and 5,880,275, herein incorporated by reference intheir entirety. In another embodiment, the structural gene can confertolerance to the herbicide glyphosate as conferred by genes including,but not limited to Agrobacterium strain CP4 glyphosate resistant EPSPSgene (aroA:CP4) as described in U.S. Pat. No. 5,633,435, hereinincorporated by reference in its entirety, or glyphosate oxidoreductasegene (GOX) as described in U.S. Pat. No. 5,463,175, herein incorporatedby reference in its entirety.

Alternatively, the DNA coding sequences can affect these phenotypes byencoding a non-translatable RNA molecule that causes the targetedinhibition of expression of an endogenous gene, for example viaantisense- or cosuppression-mediated mechanisms (see, for example, Birdet al., Biotech. Gen. Engin. Rev., 9:207, 1991). The RNA could also be acatalytic RNA molecule (i.e., a ribozyme) engineered to cleave a desiredendogenous mRNA product (see for example, Gibson and Shillito, Mol.Biotech., 7:125, 1997). Thus, any gene which produces a protein or mRNAwhich expresses a phenotype or morphology change of interest is usefulfor the practice of the present invention.

F. Definitions

In the description and tables herein, a number of terms are used. Inorder to provide a clear and consistent understanding of thespecification and claims, the following definitions are provided:

Allele: Any of one or more alternative forms of a gene locus, all ofwhich alleles relate to one trait or characteristic. In a diploid cellor organism, the two alleles of a given gene occupy corresponding locion a pair of homologous chromosomes.

Backcrossing: A process in which a breeder repeatedly crosses hybridprogeny, for example a first generation hybrid (F₁), back to one of theparents of the hybrid progeny. Backcrossing can be used to introduce oneor more single locus conversions from one genetic background intoanother.

Crossing: The mating of two parent plants.

Cross-pollination: Fertilization by the union of two gametes fromdifferent plants.

Diploid: A cell or organism having two sets of chromosomes.

Emasculate: The removal of plant male sex organs or the inactivation ofthe organs with a cytoplasmic or nuclear genetic factor or a chemicalagent conferring male sterility.

Enzymes: Molecules which can act as catalysts in biological reactions.

F₁ Hybrid: The first generation progeny of the cross of two nonisogenicplants.

Genotype: The genetic constitution of a cell or organism.

Haploid: A cell or organism having one set of the two sets ofchromosomes in a diploid.

Linkage: A phenomenon wherein alleles on the same chromosome tend tosegregate together more often than expected by chance if theirtransmission was independent.

Marker: A readily detectable phenotype, preferably inherited incodominant fashion (both alleles at a locus in a diploid heterozygoteare readily detectable), with no environmental variance component, i.e.,heritability of 1.

Phenotype: The detectable characteristics of a cell or organism, whichcharacteristics are the manifestation of gene expression.

Quantitative Trait Loci (QTL): Quantitative trait loci (QTL) refer togenetic loci that control to some degree numerically representabletraits that are usually continuously distributed.

Resistance: As used herein, the terms “resistance” and “tolerance” areused interchangeably to describe plants that show no symptoms to aspecified biotic pest, pathogen, abiotic influence or environmentalcondition. These terms are also used to describe plants showing somesymptoms but that are still able to produce marketable product with anacceptable yield. Some plants that are referred to as resistant ortolerant are only so in the sense that they may still produce a crop,even though the plants are stunted and the yield is reduced.

Regeneration: The development of a plant from tissue culture.

Self-pollination: The transfer of pollen from the anther to the stigmaof the same plant.

Single Locus Converted (Conversion) Plant: Plants which are developed bya plant breeding technique called backcrossing, wherein essentially allof the morphological and physiological characteristics of a corn varietyare recovered in addition to the characteristics of the single locustransferred into the variety via the backcrossing technique and/or bygenetic transformation.

Substantially Equivalent: A characteristic that, when compared, does notshow a statistically significant difference (e.g., p=0.05) from themean.

Tissue Culture: A composition comprising isolated cells of the same or adifferent type or a collection of such cells organized into parts of aplant.

Transgene: A genetic locus comprising a sequence which has beenintroduced into the genome of a corn plant by transformation.

G. Deposit Information

A deposit of sweet corn hybrid SV1321SD, disclosed above and recited inthe claims, has been made with the American Type Culture Collection(ATCC), 10801 University Blvd., Manassas, Va. 20110-2209. The date ofthe deposit was Mar. 10, 2014. The accession numbers for those depositedseeds of sweet corn hybrid SV1321SD is ATCC Accession Number PTA-121075.Upon issuance of a patent, all restrictions upon the deposits will beremoved, and the deposits are intended to meet all of the requirementsof 37 C.F.R. §1.801-1.809. The deposits will be maintained in thedepository for a period of 30 years, or 5 years after the last request,or for the effective life of the patent, whichever is longer, and willbe replaced if necessary during that period.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity andunderstanding, it will be obvious that certain changes and modificationsmay be practiced within the scope of the invention, as limited only bythe scope of the appended claims.

All references cited herein are hereby expressly incorporated herein byreference.

What is claimed is:
 1. A seed of corn hybrid SV1321SD, a sample of seedof said hybrid having been deposited under ATCC Accession NumberPTA-121075.
 2. A plant grown from the seed of claim
 1. 3. A plant partof the plant of claim
 2. 4. The plant part of claim 3, wherein said partis selected from the group consisting of an ear, ovule, pollen or cell.5. A corn plant, or a part thereof, having all the physiological andmorphological characteristics of the corn plant of claim
 2. 6. A tissueculture of regenerable cells of corn hybrid SV1321SD, a sample of seedof said hybrid having been deposited under ATCC Accession NumberPTA-121075.
 7. The tissue culture according to claim 6, comprising cellsor protoplasts from a plant part selected from the group consisting ofleaf, pollen, embryo, root, root tip, anther, silk, flower, kernel, ear,cob, husk, stalk and meristem.
 8. A corn plant regenerated from thetissue culture of claim 6, wherein the regenerated plant expresses allof the physiological and morphological characteristics of corn hybridSV1321SD, a sample of seed of said hybrid having been deposited underATCC Accession Number PTA-121075.
 9. A method of producing corn seed,comprising crossing the plant of claim 2 with itself or a second cornplant.
 10. A method for producing a seed of a hybrid SV1321SD-derivedcorn plant comprising the steps of: (a) crossing a corn plant of hybridSV1321SD, a sample of seed of said hybrid having been deposited underATCC Accession Number PTA-121075, with a second corn plant; and (b)allowing seed of a SV1321SD-derived corn plant to form.
 11. The methodof claim 10, further comprising the steps of: (c) selfing the plantgrown from said SV1321SD-derived corn seed or crossing it to a secondcorn plant to yield additional SV1321SD-derived corn seed; (d) growingsaid additional SV1321SD-derived corn seed of step (c) to yieldadditional SV1321SD-derived corn plants; and (e) repeating the steps of(c) and (d) to generate further SV1321SD-derived corn plants.
 12. Amethod of vegetatively propagating a plant of corn hybrid SV1321SDcomprising the steps of: (a) collecting tissue capable of beingpropagated from a plant of corn hybrid SV1321SD, a sample of seed ofsaid hybrid having been deposited under ATCC Accession NumberPTA-121075; (b) cultivating said tissue to obtain proliferated shoots;and (c) rooting said proliferated shoots to obtain rooted plantlets. 13.The method of claim 12, further comprising growing plants from saidrooted plantlets.
 14. A method of producing a plant of corn hybridvariety SV1321SD comprising an added desired trait, the methodcomprising introducing a transgene conferring the desired trait intocorn hybrid SV1321SD, whereby a plant of corn hybrid SV1321SD comprisingan added desired trait is produced, a sample of seed of said varietyhaving been deposited under ATCC Accession Number PTA-121075.
 15. Aplant of corn hybrid variety SV1321SD comprising a transgene conferringa desired trait, a sample of seed of said variety has been depositedunder ATCC Accession Number PTA-121075.
 16. A hybrid corn plant thatexhibits all of the traits of corn hybrid SV1321SD, a sample of seed ofsaid hybrid having been deposited under ATCC Accession NumberPTA-121075.
 17. A seed that produces the plant of claim
 15. 18. A seedthat produces the plant of claim
 16. 19. A method of producing a cornplant part comprising: (a) obtaining the plant of claim 1, wherein theplant has been cultivated to maturity; and (b) collecting at least afirst plant part from the plant.
 20. The method of claim 19, wherein theplant part comprises an ear.